from collections import OrderedDict
from typing import Tuple, Union

import numpy as np
import torch
from torch import nn


class Bottleneck(nn.Module):
    expansion = 4

    def __init__(self, inplanes, planes, stride=1):
        super().__init__()

        # all conv layers have stride 1. an avgpool is performed after the second convolution when stride > 1
        self.conv1 = nn.Conv2d(inplanes, planes, 1, bias=False)
        self.bn1 = nn.BatchNorm2d(planes)
        self.relu1 = nn.ReLU(inplace=True)

        self.conv2 = nn.Conv2d(planes, planes, 3, padding=1, bias=False)
        self.bn2 = nn.BatchNorm2d(planes)
        self.relu2 = nn.ReLU(inplace=True)

        self.avgpool = nn.AvgPool2d(stride) if stride > 1 else nn.Identity()

        self.conv3 = nn.Conv2d(planes, planes * self.expansion, 1, bias=False)
        self.bn3 = nn.BatchNorm2d(planes * self.expansion)
        self.relu3 = nn.ReLU(inplace=True)

        self.downsample = None
        self.stride = stride

        if stride > 1 or inplanes != planes * Bottleneck.expansion:
            # downsampling layer is prepended with an avgpool, and the subsequent convolution has stride 1
            self.downsample = nn.Sequential(OrderedDict([
                ("-1", nn.AvgPool2d(stride)),
                ("0", nn.Conv2d(inplanes, planes * self.expansion, 1, stride=1, bias=False)),
                ("1", nn.BatchNorm2d(planes * self.expansion))
            ]))

    def forward(self, x: torch.Tensor):
        identity = x

        out = self.relu1(self.bn1(self.conv1(x)))
        out = self.relu2(self.bn2(self.conv2(out)))
        out = self.avgpool(out)
        out = self.bn3(self.conv3(out))

        if self.downsample is not None:
            identity = self.downsample(x)

        out += identity
        out = self.relu3(out)
        return out


# implement attention module for v-v self-attention
class Attention(nn.Module):
    def __init__(self, out_dim, dim, num_heads=8, qkv_bias=False, qk_scale=None, attn_drop=0., proj_drop=0., settings=''):
        super().__init__()
        self.num_heads = num_heads
        head_dim = dim // num_heads
        self.scale = qk_scale or head_dim ** -0.5

        self.qkv = nn.Linear(dim, dim * 3, bias=qkv_bias)
        self.attn_drop = nn.Dropout(attn_drop)
        self.proj = nn.Linear(out_dim, dim)
        self.proj_drop = nn.Dropout(proj_drop)
        self.settings = settings

    def forward(self, x):
        B, N, C = x.shape
        qkv = self.qkv(x).reshape(B, N, 3, self.num_heads, C // self.num_heads).permute(2, 0, 3, 1, 4)
        q, k, v = qkv[0], qkv[1], qkv[2]

        # original self-attention for the original path
        attn_ori = (q @ k.transpose(-2, -1)) * self.scale
        attn_ori = attn_ori.softmax(dim=-1)
        attn_ori = self.attn_drop(attn_ori)

        # replace k & q by v
        k = v
        q = k

        # resnets have only one self-attention, norm and larger scale perform better
        if self.settings == 'resnet':
            k = k / (k.norm(p=2, dim=-1, keepdim=True) + 1e-6)
            q = k
            scale = self.scale * 8
        else:
            scale = self.scale
        
        # self-attention, higher temperate for resnets performs better
        attn = (q @ k.transpose(-2, -1)) * scale
        attn = (attn).softmax(dim=-1)
        attn = self.attn_drop(attn)

        x_ori = (attn_ori @ v).transpose(1, 2).reshape(B, N, C)
        x = (attn @ v).transpose(1, 2).reshape(B, N, C) # clip_surgery
        #x = v.transpose(1, 2).reshape(B, N, C) # mask_clip
        x = self.proj_drop(self.proj(x))
        x_ori = self.proj_drop(self.proj(x_ori))
        return [x, x_ori]


class AttentionPool2d(nn.Module):
    def __init__(self, spacial_dim: int, embed_dim: int, num_heads: int, output_dim: int = None):
        super().__init__()
        self.positional_embedding = nn.Parameter(torch.randn(spacial_dim ** 2 + 1, embed_dim) / embed_dim ** 0.5)
        self.k_proj = nn.Linear(embed_dim, embed_dim)
        self.q_proj = nn.Linear(embed_dim, embed_dim)
        self.v_proj = nn.Linear(embed_dim, embed_dim)
        self.c_proj = nn.Linear(embed_dim, output_dim or embed_dim)
        self.num_heads = num_heads

        self.attn = None
        self.embed_dim = embed_dim
        self.num_heads = num_heads
        self.output_dim = output_dim


    def forward(self, x):
        # reform transformer layer after init and load weights, using v only
        if self.attn == None:
            self.attn = Attention(self.output_dim, self.embed_dim, self.num_heads, True)
            self.attn.qkv.weight = torch.nn.Parameter(torch.cat([self.v_proj.weight, self.v_proj.weight, self.v_proj.weight], 0))
            self.attn.qkv.bias = torch.nn.Parameter(torch.cat([self.v_proj.bias, self.v_proj.bias, self.v_proj.bias]))
            self.attn.proj.weight = self.c_proj.weight
            self.attn.proj.bias = self.c_proj.bias

        x = x.reshape(x.shape[0], x.shape[1], x.shape[2] * x.shape[3]).permute(2, 0, 1)  # NCHW -> (HW)NC
        x = torch.cat([x.mean(dim=0, keepdim=True), x], dim=0)  # (HW+1)NC

        side = int((self.positional_embedding.shape[0] - 1) ** 0.5)
        new_side = int((x.shape[0] - 1) ** 0.5)

        # update the position embedding during inference for varied input size
        if side != new_side:
            new_pos = self.positional_embedding[1:, :].reshape(-1, side, side, x.shape[-1]).permute(0, 3, 1, 2)
            new_pos = torch.nn.functional.interpolate(new_pos, (new_side, new_side), mode='bilinear')
            new_pos = new_pos.reshape(-1, x.shape[-1], new_side * new_side).transpose(1, 2)
            self.positional_embedding.data = torch.cat([self.positional_embedding[:1, :], new_pos[0]], 0)

        x = x + self.positional_embedding[:, None, :].to(x.dtype)  # (HW+1)NC
        x, x_ori = self.attn(x.transpose(0, 1))

        # cls token from the original path, and img tokens from the new path
        x[:, 0, :] = x_ori[:, 0, :]
        return x


class ModifiedResNet(nn.Module):
    """
    A ResNet class that is similar to torchvision's but contains the following changes:
    - There are now 3 "stem" convolutions as opposed to 1, with an average pool instead of a max pool.
    - Performs anti-aliasing strided convolutions, where an avgpool is prepended to convolutions with stride > 1
    - The final pooling layer is a QKV attention instead of an average pool
    """

    def __init__(self, layers, output_dim, heads, input_resolution=224, width=64):
        super().__init__()
        self.output_dim = output_dim
        self.input_resolution = input_resolution

        # the 3-layer stem
        self.conv1 = nn.Conv2d(3, width // 2, kernel_size=3, stride=2, padding=1, bias=False)
        self.bn1 = nn.BatchNorm2d(width // 2)
        self.relu1 = nn.ReLU(inplace=True)
        self.conv2 = nn.Conv2d(width // 2, width // 2, kernel_size=3, padding=1, bias=False)
        self.bn2 = nn.BatchNorm2d(width // 2)
        self.relu2 = nn.ReLU(inplace=True)
        self.conv3 = nn.Conv2d(width // 2, width, kernel_size=3, padding=1, bias=False)
        self.bn3 = nn.BatchNorm2d(width)
        self.relu3 = nn.ReLU(inplace=True)
        self.avgpool = nn.AvgPool2d(2)

        # residual layers
        self._inplanes = width  # this is a *mutable* variable used during construction
        self.layer1 = self._make_layer(width, layers[0])
        self.layer2 = self._make_layer(width * 2, layers[1], stride=2)
        self.layer3 = self._make_layer(width * 4, layers[2], stride=2)
        self.layer4 = self._make_layer(width * 8, layers[3], stride=2)

        embed_dim = width * 32  # the ResNet feature dimension
        self.attnpool = AttentionPool2d(input_resolution // 32, embed_dim, heads, output_dim)

    def _make_layer(self, planes, blocks, stride=1):
        layers = [Bottleneck(self._inplanes, planes, stride)]

        self._inplanes = planes * Bottleneck.expansion
        for _ in range(1, blocks):
            layers.append(Bottleneck(self._inplanes, planes))

        return nn.Sequential(*layers)

    def forward(self, x):
        def stem(x):
            x = self.relu1(self.bn1(self.conv1(x)))
            x = self.relu2(self.bn2(self.conv2(x)))
            x = self.relu3(self.bn3(self.conv3(x)))
            x = self.avgpool(x)
            return x

        x = x.type(self.conv1.weight.dtype)
        x = stem(x)
        x = self.layer1(x)
        x = self.layer2(x)
        x = self.layer3(x)
        x = self.layer4(x)
        x = self.attnpool(x)

        # shape BNC
        return x


class LayerNorm(nn.LayerNorm):
    """Subclass torch's LayerNorm to handle fp16."""

    def forward(self, x: torch.Tensor):
        orig_type = x.dtype
        ret = super().forward(x.type(torch.float32))
        return ret.type(orig_type)


class QuickGELU(nn.Module):
    def forward(self, x: torch.Tensor):
        return x * torch.sigmoid(1.702 * x)


class ResidualAttentionBlock(nn.Module):
    def __init__(self, d_model: int, n_head: int, attn_mask: torch.Tensor = None):
        super().__init__()

        self.attn = nn.MultiheadAttention(d_model, n_head)
        self.ln_1 = LayerNorm(d_model)
        self.mlp = nn.Sequential(OrderedDict([
            ("c_fc", nn.Linear(d_model, d_model * 4)),
            ("gelu", QuickGELU()),
            ("c_proj", nn.Linear(d_model * 4, d_model))
        ]))
        self.ln_2 = LayerNorm(d_model)
        self.attn_mask = attn_mask

    def attention(self, x: torch.Tensor):
        self.attn_mask = self.attn_mask.to(dtype=x.dtype, device=x.device) if self.attn_mask is not None else None
        if isinstance(self.attn, Attention):
            x = x.transpose(0, 1)
            x, x_ori = self.attn(x)
            return [x.transpose(0, 1), x_ori.transpose(0, 1)]
        else:
            return self.attn(x, x, x, need_weights=False, attn_mask=self.attn_mask)[0]

    def forward(self, x):

        # dual paths for blocks deeper than "d"
        if isinstance(self.attn, Attention):
            if isinstance(x, list):
                x, x_ori = x
                x_res = self.attention(self.ln_1(x_ori))
                x_res, x_ori_res = x_res
                x_ori += x_ori_res
                x_ori = x_ori + self.mlp(self.ln_2(x_ori))
                x += x_res # skip ffn for the new path
                return [x, x_ori]

            # start of dual path
            else:
                x_res = self.attention(self.ln_1(x))
                if isinstance(x_res, list):
                    x_res, x_ori_res = x_res
                    x_ori = x + x_ori_res
                    x_ori = x_ori + self.mlp(self.ln_2(x_ori))
                    x += x_res
                    return [x, x_ori]

        # singl path before "d"
        else:
            x = x + self.attention(self.ln_1(x))
            x = x + self.mlp(self.ln_2(x))
        return x


class Transformer(nn.Module):
    def __init__(self, width: int, layers: int, heads: int, attn_mask: torch.Tensor = None, need_weights: bool = False):
        super().__init__()
        self.width = width
        self.layers = layers
        self.resblocks = nn.Sequential(*[ResidualAttentionBlock(width, heads, attn_mask) for i in range(layers)])

    def forward(self, x: torch.Tensor):
        return self.resblocks(x)


class VisionTransformer(nn.Module):
    def __init__(self, input_resolution: int, patch_size: int, width: int, layers: int, heads: int, output_dim: int):
        super().__init__()
        self.input_resolution = input_resolution
        self.output_dim = output_dim
        self.conv1 = nn.Conv2d(in_channels=3, out_channels=width, kernel_size=patch_size, stride=patch_size, bias=False)

        scale = width ** -0.5
        self.class_embedding = nn.Parameter(scale * torch.randn(width))
        self.positional_embedding = nn.Parameter(scale * torch.randn((input_resolution // patch_size) ** 2 + 1, width))
        self.ln_pre = LayerNorm(width)

        self.transformer = Transformer(width, layers, heads, need_weights=True)
        self.attn = None
        self.embed_dim = width
        self.num_heads = heads

        self.ln_post = LayerNorm(width)
        self.proj = nn.Parameter(scale * torch.randn(width, output_dim))

    @torch.no_grad()
    def forward(self, x: torch.Tensor):

        # reform the architecture during first inference
        if self.attn == None:
            
            # apply architecture surgery on the last 6 blocks
            for i in range(1, 7): # surgery 7, maskclip 2
                self.attn = Attention(self.embed_dim, self.embed_dim, self.num_heads, True)
                self.attn.qkv.weight.data = self.transformer.resblocks[-i].attn.in_proj_weight.clone()
                self.attn.qkv.bias.data = self.transformer.resblocks[-i].attn.in_proj_bias.clone()
                self.attn.proj.weight.data = self.transformer.resblocks[-i].attn.out_proj.weight.clone()
                self.attn.proj.bias.data = self.transformer.resblocks[-i].attn.out_proj.bias.clone()
                self.transformer.resblocks[-i].attn = self.attn

        x = self.conv1(x)  # shape = [*, width, grid, grid]
        x = x.reshape(x.shape[0], x.shape[1], -1)  # shape = [*, width, grid ** 2]
        x = x.permute(0, 2, 1)  # shape = [*, grid ** 2, width]
        x = torch.cat([self.class_embedding.to(x.dtype) + torch.zeros(x.shape[0], 1, x.shape[-1], dtype=x.dtype, device=x.device), x], dim=1)  # shape = [*, grid ** 2 + 1, width]
        side = int((self.positional_embedding.shape[0] - 1) ** 0.5)
        new_side = int((x.shape[1] - 1) ** 0.5)

        # update the position embedding during inference for varied input size
        if side != new_side:
            new_pos = self.positional_embedding[1:, :].reshape(-1, side, side, x.shape[-1]).permute(0, 3, 1, 2)
            new_pos = torch.nn.functional.interpolate(new_pos, (new_side, new_side), mode='bilinear')
            new_pos = new_pos.reshape(-1, x.shape[-1], new_side * new_side).transpose(1, 2)
            self.positional_embedding.data = torch.cat([self.positional_embedding[:1, :], new_pos[0]], 0)

        pos = self.positional_embedding.to(x.dtype)
        x = x + pos
        x = self.ln_pre(x)

        x = x.permute(1, 0, 2)  # NLD -> LND
        x, x_ori = self.transformer(x)
        x[0, :, :] = x_ori[0, :, :] # clip_surgery
        x = x.permute(1, 0, 2)  # LND -> NLD

        x = self.ln_post(x)
        x = x @ self.proj

        return x


class CLIPSurgery(nn.Module):
    def __init__(self,
                 embed_dim: int,
                 # vision
                 image_resolution: int,
                 vision_layers: Union[Tuple[int, int, int, int], int],
                 vision_width: int,
                 vision_patch_size: int,
                 # text
                 context_length: int,
                 vocab_size: int,
                 transformer_width: int,
                 transformer_heads: int,
                 transformer_layers: int
                 ):
        super().__init__()

        self.context_length = context_length

        if isinstance(vision_layers, (tuple, list)):
            vision_heads = vision_width * 32 // 64
            self.visual = ModifiedResNet(
                layers=vision_layers,
                output_dim=embed_dim,
                heads=vision_heads,
                input_resolution=image_resolution,
                width=vision_width
            )
        else:
            vision_heads = vision_width // 64
            self.visual = VisionTransformer(
                input_resolution=image_resolution,
                patch_size=vision_patch_size,
                width=vision_width,
                layers=vision_layers,
                heads=vision_heads,
                output_dim=embed_dim
            )

        self.transformer = Transformer(
            width=transformer_width,
            layers=transformer_layers,
            heads=transformer_heads,
            attn_mask=self.build_attention_mask()
        )

        self.vocab_size = vocab_size
        self.token_embedding = nn.Embedding(vocab_size, transformer_width)
        self.positional_embedding = nn.Parameter(torch.empty(self.context_length, transformer_width))
        self.ln_final = LayerNorm(transformer_width)

        self.text_projection = nn.Parameter(torch.empty(transformer_width, embed_dim))
        self.logit_scale = nn.Parameter(torch.ones([]) * np.log(1 / 0.07))

        self.initialize_parameters()

    def initialize_parameters(self):
        nn.init.normal_(self.token_embedding.weight, std=0.02)
        nn.init.normal_(self.positional_embedding, std=0.01)

        if isinstance(self.visual, ModifiedResNet):
            if self.visual.attnpool is not None:
                std = self.visual.attnpool.c_proj.in_features ** -0.5
                nn.init.normal_(self.visual.attnpool.q_proj.weight, std=std)
                nn.init.normal_(self.visual.attnpool.k_proj.weight, std=std)
                nn.init.normal_(self.visual.attnpool.v_proj.weight, std=std)
                nn.init.normal_(self.visual.attnpool.c_proj.weight, std=std)

            for resnet_block in [self.visual.layer1, self.visual.layer2, self.visual.layer3, self.visual.layer4]:
                for name, param in resnet_block.named_parameters():
                    if name.endswith("bn3.weight"):
                        nn.init.zeros_(param)

        proj_std = (self.transformer.width ** -0.5) * ((2 * self.transformer.layers) ** -0.5)
        attn_std = self.transformer.width ** -0.5
        fc_std = (2 * self.transformer.width) ** -0.5
        for block in self.transformer.resblocks:
            nn.init.normal_(block.attn.in_proj_weight, std=attn_std)
            nn.init.normal_(block.attn.out_proj.weight, std=proj_std)
            nn.init.normal_(block.mlp.c_fc.weight, std=fc_std)
            nn.init.normal_(block.mlp.c_proj.weight, std=proj_std)

        if self.text_projection is not None:
            nn.init.normal_(self.text_projection, std=self.transformer.width ** -0.5)

    def build_attention_mask(self):
        # lazily create causal attention mask, with full attention between the vision tokens
        # pytorch uses additive attention mask; fill with -inf
        mask = torch.empty(self.context_length, self.context_length)
        mask.fill_(float("-inf"))
        mask.triu_(1)  # zero out the lower diagonal
        return mask

    @property
    def dtype(self):
        return self.visual.conv1.weight.dtype

    def encode_image(self, image):
        return self.visual(image.type(self.dtype))

    def encode_text(self, text):
        x = self.token_embedding(text).type(self.dtype)  # [batch_size, n_ctx, d_model]

        x = x + self.positional_embedding.type(self.dtype)
        x = x.permute(1, 0, 2)  # NLD -> LND
        x = self.transformer(x)
        x = x.permute(1, 0, 2)  # LND -> NLD
        x = self.ln_final(x).type(self.dtype)

        # x.shape = [batch_size, n_ctx, transformer.width]
        # take features from the eot embedding (eot_token is the highest number in each sequence)
        x = x[torch.arange(x.shape[0]), text.argmax(dim=-1)] @ self.text_projection

        return x

    def forward(self, image, text):
        image_features = self.encode_image(image)
        text_features = self.encode_text(text)

        # normalized features
        image_features = image_features / image_features.norm(dim=1, keepdim=True)
        text_features = text_features / text_features.norm(dim=1, keepdim=True)

        # cosine similarity as logits
        logit_scale = self.logit_scale.exp()
        logits_per_image = logit_scale * image_features @ text_features.t()
        logits_per_text = logits_per_image.t()

        # shape = [global_batch_size, global_batch_size]
        return logits_per_image, logits_per_text
